Foldable building units have previously mostly been described in the literature. Reasons that hinder commercialization of previously described foldable building units include the large extent of work that needs to be performed at the building site, the difficulty of ensuring that prefabricated finished interior and exterior surfaces can be transported without substantial damage, and the generally increased complexity of constructing a foldable building unit.
There is, therefore, a need for foldable building units with new structural frame and connection assembly designs enabling greater construction efficiency and flexibility, in particular, structural frame and connection assembly designs allowing for easier connection of frame elements in the prefabrication process and at the building site, allowing for more finish in the factory, and less and faster work at the building site, while providing a tight building envelope with reduced heat transfer, particularly, through the edges of the foldable building unit.